Structural, energetic and vibrational properties of some van der Waals complexes of CO₂, OCS and OCSe

Abstract

As part of a study of the properties of some chalcogen-bonded complexes with NH₃, H₂O, PH₃ and H₂S, we have investigated the oxygen-bound species containing CO₂, OCS and OCSe by means of molecular orbital calculations at the ab initio level. The structures of the NH₃, H₂O and PH₃ complexes are all similar, with a primary C…X interaction (X = N, O, P) and one of the hydrogen atoms approaching an oxygen atom in a weak secondary attraction. The H₂S complexes show a greater variety of alternative structures. The changes in the monomer geometrical parameters, the interaction energies and the harmonic vibrational spectra vary in general in a systematic way as the acid and the base are changed. Deviations from this systematic behaviour have been rationalised.

Keywords:

• ab initio calculations
• molecular complexes
• molecular structures
• interaction energies
• vibrational spectra

Acknowledgements

The grant holder acknowledges that opinions, findings and conclusions or recommendations expressed in any publication generated by National Research Foundation of South Africa (NRF) supported research are those of the authors and that the NRF accepts no liability in this regard. They would also like to acknowledge helpful comments from the referees.

Additional information

Funding

This work is based on research supported in part by the National Research Foundation of South Africa (NRF) under grant number 2053648. The authors also acknowledge financial assistance from the University of Mauritius and the University of KwaZulu-Natal Research Fund, and the Centre for High Performance Computing (South Africa) for the use of computing facilities.